Various user authentication technologies are known for restricting access to a mobile device. These may include, for example, passwords, facial recognition, and voice authentication.
For voice authentication, the user speaks a word or phrase. The device analyzes the frequency content of the voice signal to generate a voice print. The device compares this voice print against a pre-recorded voice print to assess whether the speaker is the authorized user of the device.
One security weakness of this voice authentication technology is that an unauthorized person may gain access to the device by playing a recording of the user's voice. One improvement of the voice authentication technique is to require the user to speak a password or passphrase which the user keeps secret. This makes it more difficult, but not impossible, for unauthorized users to gain access to the device. Accordingly, further security enhancements for voice authentication remain highly desirable. One such improvement is disclosed in this specification.
It will be noted that throughout the appended drawings, like features are identified by like reference numerals.